Even though the try/except is Django 2.0 compatible, it still
accesses the deprecated template tag, and therefore it emits a
warning in the console, whereas it's actually fixed.
I tried to swap the try and the catch, but it doesn't work:
`simple_tag` existed before 1.9 but in a non-compatible form.
I've changed the decorator name we use to match the new Django version,
it should make the codebase more future proof.
abbb666eae